Michael Hoffman - Biodegradable conductors on biodegradable polymer foils

Session 9: Conductors I

Biodegradable conductors on biodegradable polymer foils
Wednesday, June 21, 2017 
11:10 AM - 11:30 AM

For various types of applications, flexible electronics devices are desirable which need to operate only a few days and decompose afterwards. Examples are medical implants which are absorbed by the living organism or devices that can be recycled by industrial composting facilities. Key components of such devices are suitable substrates and conductive tracks. As substrate material, polylactic acid (PLA) is a common choice since it is clinically approved for absorbable implants and it is established as being biodegradable according to EN 13432. As conductor material, magnesium also is a well-established material for absorbable implants. We show how conductive tracks of magnesium can be produced by vacuum thermal evaporation onto PLA foils. A direct deposition onto pristine PLA foils does not yield any film due to poor sticking. The sticking behavior can be improved by seed layers, by high energy plasma pretreatment and by outgassing. Whereas a planar layer of Mg can be achieved already by moderate pretreatment, the production of narrow structures requires a combination of methods. In this way, we are able to produce conductive tracks of 120 µm nominal width which show a resistance corresponding to 2 Ohm/square at 50 nm Mg thickness. This is on the same order as the sheet resistance of comparable planar Mg layers on glass.


Speaker's Biography

Dr. Michael Hoffmann received his Ph.D. in physics at TU Dresden in 2000. He continued with basic research on optical spectroscopy of organic semiconductors at the Department of Chemistry, Princeton University until 2001 and at Institut für Angewandte Photophysik (IAPP), TU Dresden until 2006. Then, he joined Fraunhofer Gesellschaft, where we worked in the field of organic electronics. Currently, he is senior scientist at Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP in Dresden.


Michael Hoffmann
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP